S. T. A. M. P
S = Size
T = Temperature
A = Application
M = Material to be conveyed
P = Pressure
The hose I.D. must be sized accurately to obtain the proper flow velocity. A flow that's too slow results in sluggish system performance and a flow that's too high causes excessive pressure drops, system damage, and leaks.
Usually Dash Numbers or Dash Sizes are used to identify hose and fitting size. The Dash Number is the measure of a hose's Inner Diameter (I.D.) in sixteenths of an inch.
To find out the hose size, check the layline. If the original printing has worn off, the original hose must be cut and the inside diameter measured. Be sure to measure the overall assembly length and fitting orientation before cutting the hose.
Both media temperature (the temperature of the media conveyed through the hose) and the ambient temperature (the temperature around the hose where it is being used) need to be considered when selecting the hose. Make sure that temperature rating of the hose you are considering meets or exceeds the higher of the media or ambient temperature of your application.
Also, make sure you consider media type along with media temperature because different fluids can increase or decrease the effects of temperature on the hose.
Before selecting a hose, it is important to consider how the hose assembly will be used. Answering the following questions may help:
What type of equipment is the hose going to be used on?
What environmental factors will the hose be exposed to?
Are mechanical loads applied to the assembly?
Will the routing be confined?
Is there a need to use field attachable fittings?
Will the assembly be subjected to abrasion?
Governmental agencies control additional standards for particular industries such as the United States Coast Guard and the American Bureau of Shipping. You must select a hose that meets the legal requirements as well as the functional requirements of your application.
The hose you order must be compatible with the medium being conveyed. Compatibility must cover not just the inner tube, but the cover, hose fittings, and o-rings as well.
It is important to know both the system working pressure and any surge pressures and spikes. Select a hose with the published maximum working pressure equal to or greater than the maximum system pressure AND any surge pressures or peak transient pressures in the system.
When selecting components of a hose assembly, you must look at the "weakest link" of the assembly. A hose assembly is rated at the maximum working pressure of its component with the lowest pressure ratin